1. Field of the Invention
The present invention relates to communication systems, and more particularly to an apparatus and method for performing an interworking function between at least two networks.
2. Description of the Related Art
Many networks differ in terms of their communication protocols. For example, in a wideband code division multiple access (WCDMA) network, voice and/or video data is forwarded to an AAL2 (ATN adaptation layer 2) cell. In an IP network, voice data is forwarded using a voice over IP (VoIP) service, where IP stands for Internet Protocol. VoIP is a term used in IP telephony for a set of facilities that deliver voice information using an Internet Protocol. Typically, this involves sending voice information in digital form in discrete packets, rather than according to traditional protocols of, for example, a public switched telephone network (PSTN).
FIG. 1 is a diagram of a typical VoIP network. As shown, a codec and IP connection device are connected to the IP network. In such a configuration, signals (e.g., voice or fax) are processed in a data format compatible with the IP network and then are sent through the IP network. The codec encodes voice or fax data into packets having a predetermined length in one direction, and decodes packetized data into voice or fax data in a reverse direction.
In one direction, the IP connection device (A) sends the data packetized in the codec over the IP network to another IP connection device (B) performing a VoIP function. In the reverse direction, the IP connection device (A) receives packets from the other IP connection device (B) over the IP network and forwards them to the codec.
FIG. 2 is a diagram of an AAL2 in a WCDMA system. As shown, a codec and an AAL2 (ATM adaptation layer Type 2) data processor are connected to a WCDMA network. In such a configuration, voice and/or video signals are processed in a data format compatible with the WCDMA network and then sent through the WCDMA network. In this system, the codec encodes voice and/or video data into packets of a predetermined length for transmission on the network, and decodes packets received from the network into voice and/or video data.
The AAL2 data processor assembles data from the codec into an AAL2 cell, and then forwards the cell for transmission over the WCDMA network. When an AAL2 cell is received from an AAL2 data processor of another station, it is disassembled into data packets, and then the codec decodes the packets back into voice and/or video data.
From the foregoing discussion, it is therefore apparent that each communication network performs data transmissions based only on their own protocols. That is, a VoIP network can implement voice service only with terminals that can access that VoIP network. Similarly, a WCDMA network can implement voice and/or video services only with terminals that can access that WCDMA network. There is no provision that will allow voice or data service to be provided through VoIP and WCDMA networks. Thus, when it is desirable to send data (e.g., voice, fax, video, etc.) from one type of network to another, no compatibility exists between the networks to do so.